An actuating drive of this type is known, for example, from DE 102 51 225 A1. In this prior art a fuel-resistant sealing ring (O-ring) is inserted in openings of a head plate placed on the piezo actuator in order to create a permanent, in particular oil-tight, seal between a piezo actuator and an external terminal. Furthermore, a sleeve of insulating material, which effects centering and electrical insulation of the contact pin, is inserted in each opening below the sealing ring.
A further contacting arrangement for electrically connecting contact pins of a piezo actuator to laterally projecting connection pins of an external connection device is known, for example, from DE 198 44 743 C1. This publication describes a contact carrier with bores for the contact pins to pass through and with welding lugs arranged adjacent to the bores in such a way that they can be welded to the protruding contact pins. The welding lugs of the contact carrier are connected electrically to laterally projecting contacts which can therefore be used for external connection of the finished fuel injector. After welding of the contact pins to the welding lugs, in this prior art the manufacturing step of injection-molding plastics material around the upper side of the contact carrier is provided.
The known injection-molding around a contacting and/or sealing arrangement on an actuating drive is comparatively simple to execute and advantageously protects the actuating drive components located underneath.
A disadvantage of the known covering by means of injection-molding, however, is that the actuating drive components covered by the injection-molded plastics material frequently have to be configured in a special way (with increased complexity and cost). For example, in the contact carrier according to the above-mentioned DE 198 44 743 C1, special sealing of the bores of the contact carrier against ingress of plastics material during injection molding is provided.
Independently of this, it has emerged, especially in the case of actuating drives with a piezo actuator, that the service life of the actuator tends to be negatively influenced by sealing elements for sealing the actuator space, and by final injection molding of plastics material around the contacting and/or sealing arrangement, and thus by the more-or-less hermetic sealing of the actuator.